The sister of one of America's top fighter pilots said that the Air Force is tarnishing her brother's memory by blaming him for the crash that took his life rather than the plane that cut off his oxygen supply mid-flight -- the same troubled fighter plane that represents a $79 billion Air Force investment with a major defense contractor.

"I'd like to think it's easier to blame Jeff. He's not here to defend himself," Jennifer Haney, sister of the late Capt. Jeff Haney and family spokesperson, told ABC News in an exclusive interview to be broadcast on "Nightline" tonight. "To them, Jeff was a number, it feels like sometimes. But those jets are worth a lot of money."

Today the Air Force officially received the last F-22 Raptor from defense contracting giant Lockheed Martin, completing an order of 187 planes that cost U.S. taxpayers an estimated $79 billion -- meaning that including research, development and production among other costs, each plane has a price tag of more than $420 million.

Despite the Air Force's glowing descriptions of the jet as America's future of air dominance, critics told ABC News the pricey plane was a waste of money in today's combat environment and, more importantly, it could be more of a danger to its own pilots. As an ABC News investigation found, unknown problems with the plane have already contributed to the death of one pilot, the near-death of another and mid-air scares for dozens more.

The F-22 Raptor, America's most expensive fighter, is the subject of an ABC News investigation airing tonight on "World News With Diane Sawyer" at 6:30 p.m. ET and then "Nightline" at 11:35 p.m. ET.

F-22 Pilot Blamed in Fatal Crash After Plane Malfunction

Capt. Jeff Haney was flying the Air Force's next-generation stealth F-22 Raptor on a routine training mission in Alaska in November 2010 when a sudden malfunction cut off his oxygen completely. Capt. Haney never made a distress call but took his plane into a dive and, a little over a minute later, crashed into the winter wilderness at faster than the speed of sound.

After a lengthy investigation, an Air Force Accident Investigation Board could not find the cause of the malfunction but determined "by clear and convincing evidence" that in addition to other factors, Haney was to blame for the crash because he was too distracted by his inability to breathe to fly the plane properly.

But Haney's sister, Jennifer, told ABC News she believes her brother blacked out trying to save himself and said that by blaming him, the Air Force was attempting to deflect attention from an ongoing, mysterious oxygen problem with the costly planes.

"I don't agree with [the Air Force]. I think there was a lot more going on inside that cockpit," Jennifer Haney said. "A cover-up? I don't know. But there's something."

In at least 25 cases since 2008, F-22 pilots have reported experiencing "hypoxia-like symptoms" in mid-air, according to the Air Force. Last year the Air Force grounded the full fleet of F-22s for nearly five months to investigate, but still no one knows what is going wrong, even as the planes are back in the air. Hypoxia is caused by a lack of oxygen to the brain and is characterized by dizziness, confusion, lack of judgment and, eventually, unconsciousness.

In one case before the grounding, a pilot became so disoriented that his plane dropped down and skimmed treetops before he managed to save himself and return to base, an Air Force spokesperson told ABC News. Earlier this week, a top Air Force official told reporters that a "very small number" of F-22 pilots had requested not to fly the plane anymore because of concerns with the oxygen system.

Top officials at the Air Force and Lockheed Martin refused to take part in one-on-one interviews with ABC News for this report, but the Air Force provided a statement in which it says the service is committed to "unparalleled dedication to flight safety."

"Flying America's premier fighter aircraft always entails risk but the Air Force has, and always will, take every measure to ensure the safety of our aircrews while delivering air superiority for the nation," the statement said. The Air Force has also stressed that reports of "hypoxia-like symptoms" are exceedingly rare -- more than two dozen compared to the thousands of flights flown without incident.

The Pentagon had originally ordered hundreds more of the planes from Lockheed Martin, but in 2009 high-powered critics of the program from across the political spectrum -- from Sen. John McCain to President Barack Obama -- pressured Congress to cancel further funding for F-22s beyond the 187 already ordered, saying that the enemy the F-22 was designed to fight -- rival, super-sophisticated fighter jets in great numbers -- simply doesn't exist.

"I think [the F-22] ensures air dominance... but I guess the question that needs to be asked in return is, where is the threat?" Sen. McCain told ABC News recently. "Unless you believe that al Qaeda is going to have a fleet of aircraft…"

Recently, several of the planes have been deployed to a base in the United Arab Emirates just a short hop over the Persian Gulf from Iran in what the Air Force called a regular, scheduled deployment. Last year, the vice president of Lockheed Martin's F-22 program told ABC News the stealth fighter could "absolutely" find a home in quick strike missions against high security targets like North Korea or Iran.

The Air Force has claimed the F-22 is ready to go to war should it be called but also admitted several training operations have been aborted due to the hypoxia concerns.